Patent GB-1223013-A (GB)
Title: Arrester gear for vehicles
Inventor: STEVENS GEOFFREY WILLIAM HEDGE
IPC: B64F1/02
Filed: 1968-03-26
Abstract: 1,223,013. Arresting aircraft. MINISTER OF TECHNOLOGY. 26 March, 1969 [26 March, 1968], No. 14591/68. Heading B7G. [Also in Division F2] Aircraft arresting gear comprises aircraftengaging means (e.g. a net-type barrier 57, Fig. 5), for extending across the possible path of an aircraft, and at least one fabric shock-absorbing device having two opposed plies or face layers which are joined to each other by interconnecting pile members and wherein one face layer is secured at one end to a datum anchorage such as the ground or a ship hull (e.g. at 54, Fig. 5) and the other face layer is joined at a corresponding one end (e.g. at 58, Fig. 5) to the aircraft-engaging means, so that upon engagement of an aircraft with the aircraft-engaging means, continued movement of the aircraft is resisted by tearing or ripping of the interconnecting pile members. Preferably, as shown, one anchored fabric shock-absorbing device is connected to each end of the aircraft-engaging means. Further anchorages 52, Fig. 5, for the respective joined ends may be provided. The net-type barrier may be formed, at least in part, of the same fabric material as the fabric shock-absorbing devices. Additional shock-absorbing means such as drag parachutes may be employed. In Fig. 3 an aircraft travelling in direction C  along a runway 35 first encounters a net 38. The net is erected between a pair of secondary fixed anchorages 42 to which it is secured by breakable ties 43. Fabric material 44 has divided lengths of face plies 36 and 37 which are connected to each end of net 38 at 39 and to final anchorages 40 respectively. On encounter, the ties 43 break, and the first arresting force exerted on the aircraft is by two parachutes 33 each secured to the joined ends of a pair of plies and each rigged ready for use in a partially unfurled condition, supported in a vertical plane between uprights (not shown) with its mouth 34 facing and parallel to runway 35. The aircraft engaged by the net 38 continues along the runway under the braking force of the parachutes until the divided lengths of face plies 36, 37 come under tension (at a point well beyond anchorages 40), whereupon braking force according to the invention is applied through net 38 as interconnecting pile members 46 are ripped or torn with continuing motion of the aircraft. For speeds in the range above about 100 feet/sec. additional drag lines 47 may be incorporated to alleviate the loads in the fabric material 44. As the speed of the aircraft is reduced, the drag efficiency of the parachutes decreases, but this can be compensated for by providing a progressively increasing width of tearing as the speed is reduced, as shown in Figs. 5 and 6. Three lengths of fabric material are secured at their "joined" ends to vertical secondary anchorages 52 at each side of a runway R. The outer face plies 53a, 53b and 53c are secured to primary, or datum, anchorages 54 and the inner face plies 55a, 55b and 55c are secured to the members 56a, 56b and 56c respectively, which are each secured to the net 57. Interconnecting pile members are absent as far as the lines 59a, 59b and 59c respectively from the anchorages 54. Clusters of three drag parachutes are also connected to net 57 at 58. When an aircraft travelling in direction D is engaged by net 57, drag forces are initially applied by the parachutes and tearing of the pile members of fabric lengths 53a. As the speed of the aircraft is reduced and the drag parachutes become less effective, additional drag forces are applied successively by the interconnecting pile members of fabric lengths 53b and 53c respectively. In Fig. 7 (not shown), the fabric lengths lie largely on the ground, and the anchorages are horizontal and at ground level. In Fig. 2 (not shown), only one fixed anchorage is provided for each of the two fabric shockabsorbing devices, and the two anchorages and the two junctions with the net, and the net itself, are all aligned. Each fabric device then extends backwards, parallel to the runway, and a parachute is provided at its free end. Reference has been directed by the Comptroller to Specification 1,166,245.